feat(connect langgraph to mcp tools):

Author: NicholasGoh

backend/api/routers/llms.py

@@ -3,6 +3,7 @@
 import psycopg.errors
 from fastapi import APIRouter
 from langchain_core.messages import HumanMessage
+from langchain_mcp_adapters.tools import load_mcp_tools
 from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
 from psycopg_pool import AsyncConnectionPool
 from sse_starlette.sse import EventSourceResponse
@@ -12,6 +13,7 @@
 from api.core.config import settings
 from api.core.dependencies import LLMDep
 from api.core.logs import print, uvicorn
+from api.routers.mcps import mcp_sse_client
 
 router = APIRouter(tags=["chat"])
 
@@ -68,9 +70,15 @@ async def stream_graph(
     ) as pool:
         checkpointer = await checkpointer_setup(pool)
 
-        graph = get_graph(llm, checkpointer=checkpointer)
-        config = get_config()
-        events = dict(messages=[HumanMessage(content=query)])
-
-        async for event in graph.astream_events(events, config, version="v2"):
-            yield dict(data=event)
+        async with mcp_sse_client() as session:
+            tools = await load_mcp_tools(session)
+            graph = get_graph(llm, tools=tools, checkpointer=checkpointer)
+            config = get_config()
+            events = dict(messages=[HumanMessage(content=query)])
+
+            async for event in graph.astream_events(
+                events, config, version="v2"
+            ):
+                if event.get("event").endswith("end"):
+                    print(event)
+                yield dict(data=event)